ras p21 is a member of the small GTP-binding protein (G-protein) superfamily. ras proteins are thought to regulate key signalling pathways involved in cell growth and development. ras proteins reside on the inner surface of the plasma membrane where they participate in transmitting signals from tyrosine kinase receptors and some receptors coupled to heterotrimeric G proteins.
Because mutated ras proteins have been found in lung, bladder, colon, and many other human carcinomas, and are associated with human carcinogenesis, it is of value to study the processes by which ras mediates cell proliferation and differentiation. One approach to dissecting ras function is to identify and study the molecules that interact with ras, specifically the regulatory and effector molecules of ras p21. Knowledge of the interacting proteins in the ras signaling pathway will allow the screening of drugs for agonists and antagonists of ras-dependent cell proliferation and differentiation. Until recently, the hunt for direct downstream targets through which ras acts has not been fruitful. The discoveries of the present invention provide tools useful to elucidate the mechanism of ras signaling and new approaches to modulate ras activity and to alleviate disease conditions due to ras dysfunction.